Espresso Tonic Recipe

Before you start

An espresso tonic is a tall, fizzy, bittersweet drink: tonic water over ice with espresso floating in a dark band on top. The quinine bitterness and citrus notes in the tonic pull fruity, bright flavors out of the coffee, and the bubbles make it feel lighter than an iced coffee.

The main challenge is foam. Hot espresso poured quickly into carbonated water releases a surge of bubbles that can overflow the glass. Keep the tonic very cold, fill the glass with ice to slow the pour, and add the shot slowly over the back of a spoon. A light or medium roast with fruity notes suits the tonic better than a dark, roasty blend.

Ingredients

• 150 ml (5 oz) tonic water — well chilled; a less sweet craft tonic works well
• 1 heaping cup (about 150 g) ice cubes
• 18 g espresso coffee beans — light or medium roast, ground fine
• about 36 g (1¼ oz) water, as brewed espresso — a double shot
• 1 strip orange or grapefruit peel — optional

Method

1. Fill a tall glass to the top with ice. A glass full of ice keeps the tonic cold and gives the espresso something to land on.
2. Slowly pour in the chilled tonic water, tilting the glass so it does not foam, until it is about two-thirds full.
3. Pull a double shot of about 36 g in 25 to 30 seconds into a small spouted pitcher. Let it rest for 15 to 20 seconds so it is not scalding.
4. Hold a bar spoon upside down just above the tonic and pour the espresso very slowly over its back. The coffee should spread in a brown layer over the clear tonic.
5. Twist the citrus peel over the top to release its oils, drop it in, and serve unstirred.

Tips for success

• Pour the espresso into a small pitcher and let it cool briefly. Slightly cooler espresso releases less gas from the tonic and foams less.
• Use tonic from a freshly opened bottle. Flat tonic will not layer cleanly and tastes overly sweet.
• If a fizz cap forms, wait a few seconds before adding the rest of the espresso. The foam settles quickly.

Substitutions

Tonic water

Light or diet tonic makes a drier drink. Soda water with 10 ml of simple syrup gives the fizz without the quinine bitterness.

Espresso

Chilled cold brew concentrate, about 45 ml, layers easily and foams much less, though it tastes rounder and less bright.

Citrus peel

A sprig of rosemary or thyme adds an herbal aroma that suits fruity, light-roasted coffee.

Variations

Grapefruit espresso tonic

Add 30 ml fresh grapefruit juice to the tonic before layering the espresso.

Elderflower espresso tonic

Stir 10 ml elderflower cordial into the tonic for a floral, slightly sweeter drink.

Troubleshooting

It foamed up and overflowed

The espresso went in too fast or too hot. Let it rest in a pitcher and pour it slowly over a spoon onto a full glass of ice.

It tastes harsh and medicinal

A dark roast and a very bitter tonic compound each other. Switch to a light roast or a milder tonic.

No layers, just a muddy color

The tonic was warm or the pour was too heavy. Chill the tonic well and aim the espresso at the spoon.

Storage

Serve at once; the carbonation fades within minutes and the layers merge. Recap opened tonic bottles tightly and refrigerate them, using within a day or two while still fizzy.